dawson



Feb. 14. 1956 E. w. DAWSON RECIPROCATING AND ROTATING BLADE POLISHER Filed Nov. 22, 1954 INVENTOF? E. w. DAWSON ATTYS Ufliwd S tes PatenfQr RECIPROCATING AND ROTATING BLADE POLISHER Application November 22, 1954, Serial No. 470,397

6 Claims. (Cl. 51-7) This invention relates to a device for polishing small parts.

In manufacturing metal parts to fine tolerances it is often necessary to polish the part without removing an appreciable amount of material. This process is considerably complicated if the part is of irregular form. Blades for gas turbine engines, for example, require a high degree of polishing, but due to their shape, present unusual problems during this operation.

It is an object of the present invention to provide a device for polishing small parts such as gas turbine blades which will enable each blade to be polished individually to the desired degree.

According to the invention a part holder is provided surrounded by a container for polishing compound, means are provided to rotate the part holder and container and means are provided to axially reciprocate the said part holder and container.

A preferred embodiment of the invention is illustrated in the accompanying drawings in which like reference numerals denote like parts in the various views and in which:

Fig. 1 is a side elevation, partly cut away, and

Fig. 2 is a detail of Fig. 1.

Referring now to the drawings it will be seen that a sleeve 12 is supported above a base by means of a pair of flexible leaf springs 11. The base 10 has upwardly extending projections 13 and the sleeve 12 has downwardly extending projections 14 in which the springs 11 are fastened by means of bolts 16.

A shaft 17 is journalled for rotation within the sleeve 12 and terminates at one end in a pulley 18 and at the other in a part holder 19. A motor 20 and a speed reducer 21 are mounted below the base 10 and a belt or chain extends between a pulley 22 on the speed reducing shaft and the pulley 18 on shaft 17.

A can or container 23 is secured to the shaft 17 in such a manner that it surrounds the part holder 19 and is rotatable therewith. The can 23 contains the polishing compound 40 which may comprise any of the known polishing mediums. A part 24 is shown held by the part holder and, in the illustration, comprises a gas turbine blade. A shield 25 is secured to the end of the container to protect the end of the part from the abrasive action of the compound.

Secured to the sleeve 12 by means of a pivot joint 26 is an arm 27 which is connected by pivot joint 28 to a crank or eccentric 29. This eccentric 29 is driven by means of a belt or chain 30 which is engaged with the shaft of a motor 31. The speed of the motor 31 is not reduced and the reciprocation which results from the rotation of eccentric 29 is, therefore, rapid in comparison with rotation of shaft 17. The shaft 17 is provided with rotation and thrust bearings 41 within the sleeve 12 so that it is caused to reciprocate with the sleeve 12 as well as to rotate by virtue of its connection with motor 20.

In Fig. 2 there is shown the bearing at the end of sleeve 12 adjacent the container 23. A similar bearing 41 is 2,734,316 PatentedFeb. 14,v 1956 positioned at the opposite end of shaft 17. The shaft 17 is provided with a radially extending flange 32 at the part holding end through which bolts 33 pass in holes provided therefor; The bolts 33 also pass through the end wall of the container 23 and engage in an outwardly extending flange 34 on the part holder 19. A key 35 is provided at the end of the part holder 19 which engages in a coooperating' key way'36 in the end of shaft 17.

The inner walls of container 23 may "be provided with ribs 37 which'will serve, when the container is rotated, to prevent settling of the polishing compound due to gravitational etfects.

In operation, a part 24 is placed in the part holder 19 by removing the end 38 of the can 23 and inserting the part in the jaws 39 of the part holder. The container is then filled to the desired level with the polishing compound 40 and the end 38 is replaced upon the container 23. The motor 20 is then energized so that the shaft 17 and the container 23 rotate slowly about their longitudinal axis. The motor 31 is then energized and the eccentric 29, by means of shaft 27, causes the rapid reciprocation of the sleeve 12 and hence the shaft 17 The flexible leaf springs 11 enable the sleeve 12 and the shaft 17 to be displaced axially by a distance equal to the radius of eccentricity of the crank 29. The inertia of the polishing compound 40 will cause it to move relative to the part 24 during the reciprocating action and have a polishing effect on the part. The rotation of the container 23 will prevent settling of the mixture due to the gravitational effect.

By varying the speed of motor 31 and motor 20 the polishing action can be accelerated or retarded at will. The device which has been disclosed can, of course, be produced in multiple units so that two or more blades can be polished simultaneously. In this event it is important that each polishing unit can be disconnected from the source of motive power so that a polished part may be removed and an unpolished part inserted in one unit without disturbing the operation of the remaining units.

From the foregoing description it will be seen that a polishing device has been invented which will enable a part to be individually polished to any desired degree.

What I claim as my invention is:

l. A polishing device for small parts comprising a base, a sleeve resiliently mounted on the base, a shaft journalled in the sleeve for rotation relative thereto but fixed against axial movement relative to the sleeve, a part holder fixed to one end of the shaft, a can adapted to contain a polishing compound surrounding the part holder and fixed to the shaft, means to rotate the shaft and means to reciprocate the sleeve.

2. A polishing device for small parts comprising a base, a sleeve resiliently mounted on the base for axial displacement, a shaft journalled in the sleeve for rotation relative thereto but fixed against axial movement relative to the sleeve, 21 part holder fixed to one end of the shaft and adapted to hold a part in position with its axis parallel to the axis of the shaft, a can adapted to contain a polishing compound surrounding the part and part holder and fixed to the shaft, means to slowly rotate the shaft and means to rapidly reciprocate the sleeve.

3. A device as claimed in claim 2 in which the axis of the part held by the part holder is a continuation of the axis of the shaft.

4. A polishing device for small parts comprising a base, a sleeve resiliently mounted on the base for axial displacement, a shaft journalled in the sleeve for rotation relative thereto but fixed against axial displacement relative to the sleeve, a part holder fixed to one end of the shaft and adapted to hold a part in a position with its axis coextensive with the axis of the shaft, a can adapted to contain a polishing compound surrounding the part and the part holder and fixed to the shaft, a shield extending towards the part from the end of the can remote from the part holder, the end of the shield lying in juxtaposition to the end of the part to protect the end face of the part from the action of the polishing compound, means to slowly rotate the shaft and means to rapidly reciprocate the sleeve.

5. A polishing device as claimed in claim 4 in which the means to slowly rotate the shaft include an electric motor, a reduction gear train and a belt passing over pulleys on the output shaft of the gear train and the shaft of the polishing device.

6. A polishing device as claimed in claim 4 in which the means to reciprocate the sleeve include an electric motor driving a crank, a connecting rod pivotally connected at one end to the sleeve and pivotally connected at the other end to the throw of the crank.

References Cited in the file of this patent UNITED STATES PATENTS 1,310,071 Gurry July 15, 1919 1,872,812 Regero Aug. 23, 1932 2,387,140 Fruth Oct. 16, 1945 2,435,488 Baylin Feb. 3, 1948 

